Clinical evidence indicates clearly that some preterm infants whether healthy or ill, are more physiologically stressed by handling than are others of the same gestational age. Age alone is not a sufficient criteria on which care to these fragile infants can be based. However, there are not few reliable and valid assessment tools which can be used to plan appropriate care. The purpose of this project is to develop a clinically useful assessment tool by characterizing in detail one facet of infant behavior, nutritive sucking, which can serve as an index of neurobehavioral integrity in the full term and preterm infant. The specific aims are: 1) develope normative data base; 2) examine the relationship of gestational age to changes in sucking patterns; 3) examine the relationship of cardiovascular parameters and behavioral state, concurrent measures of neurobehavioral organization, to nutritive sucking; and 4) investigate the physiologic stress associated with nutritive sucking in preterm infants. The sample will include 300 full term and preterm infants with post-conceptual ages at the time of measurement ranging from 32 to 40+ weeks. The data collections instruments include the Kron Nutritive Sucking Apparatus, Nellcor pulse oximeter, Dinamapp blood pressure monitor, and the Anderson Behavioral State Scale. Infants in the full term nursery will have a 5 minute sucking measurement completed on the first and second days of life. Preterm infants in the intermediate care nursery will have weekly sucking measurement from 32-33 weeks until hospital discharge. Cardiovascular measurements and behavioral state will be measured concurrently. Data analysis will include means, standard deviations, standard error of the means, t-tests, MANOVAs and ANOVAs with repeated measures. It is anticipated that this investigation will (a) provide clinicians with a means of assessing neurobehavioral development through sucking behaviors; (b) supply clinically useful information on maturational changes of sucking patterns in preterm infants; and (c) provide new information on the relationship of cardiovascular parameters and behavioral state with nutritive sucking. This research will lead to the development of a clinically useful tool for the assessment of neurobehavioral status in the neonatal period.